9,953 research outputs found
Chromium recovery by membranes for process reuse in the tannery industry
Leather tanning is a wide common industry all over the
world. In leather processing, water is one of the most
important medium, almost 40-45 L water kg-1 raw-hide or
skin is used by tanneries for processing finished leathers.
The composition of tannery wastewater presents
considerable dissimilarities in the concentration range of
pollutants both of inorganic (chlorides, with concentration
ranging from several hundred to over 10,000 mg L-1 Cl–;
sulphate (VI), ammonium ions and sulphide ions,
exhibiting concentration that ranges from tens to several
hundred mg L-1) and organic (the COD value is usually
several thousand mg L-1 O2). Throughout the years, many
conventional processes have been carried out to treat
wastewater from tannery industry: unfortunately, in this
case, biological treatment methods give rise to an
excessive production of sludge, whereas physical and
chemical methods are too expensive in terms of energy and
reagent costs. In this work, a membrane process based on
NF membrane modules was adopted to treat the tannery
feedstock after primary conventional treatment. In a first
step, the determination of all boundary flux parameters, in
order to inhibit severe fouling formation during operation,
were performed. After this, experimental work was carried
out to validate the approach. The target of water
purification was reached, that is the legal discharge to
municipal sewer system in Italy of 90% of the initial
wastewater stream volume. This allows having an
immediate cost saving of 21%. Moreover, the developed
process leads to a second benefit, that is the production of
5% of the initial volume as a highly chromium-rich
concentrate at no cost suitable to tannery process recycle
and reuse. In this case, cost saving rates exceeds 40%. At
the end, scale-up of the investigated process will be
discussed from technical and economic point of view
Entanglement between two superconducting qubits via interaction with non-classical radiation
We propose a scheme to physically interface superconducting nano-circuits and
quantum optics. We address the transfer of quantum information between systems
having different physical natures and defined in Hilbert spaces of different
dimensions. In particular, we investigate the transfer of the entanglement
initially in a non-classical state of a continuous-variable system to a pair of
superconducting charge qubits. This set-up is able to drive an initially
separable state of the qubits into an almost pure, highly entangled state
suitable for quantum information processing.Comment: 4 pages, RevTeX; revised versio
Distribution and abundance of hard clam shells Meretrix meretrix along the coastal areas of Panguil bay, Lanao del Norte, Philippines
Abstract only.Meretrix meretrix is believed to be abundant in Panguil Bay and in the absence of relevant fishery statistics, it is useful to quantify their biomass with a view to determining their fishery potential. This study aims to monitor the gonadal development, identify the associated macrofauna and determine the distribution and abundance of hard clam shells M. meretrix along the coastline of four municipalities of Lanao del Norte at Panguil Bay. Four sampling sites were selected and established to achieve and relate some generalities using the transect-quadrat method. Clams were counted, measured and identified. Physicochemical parameters were also noted every sampling. M. meretrix was found to be most abundant in Raw-an Pt. Baroy (28-542 pcs./m2) followed by Mayao, Lala (0.3-26 pcs/m2). M. meretrix at Aloha Tubod occurred in low densities (0.1-4 pcs/m2). No hard clam shell was found in Taguitic, Kapatagan. Mean length differed significantly at the three locations. The coastal area of Mayao, Lala, had the highest diversity (H' = 4.236737) in terms of shell species identified and recorded during the twelve months sampling period. Most of the shells dissected were sexually immature with male shellfishes being more predominant than females. Differences in distribution, density and length size of hard clam shells were compared in this study at four locations. Anthropogenic causes e.g. exploitation as well as environmental parameters such as salinity levels and sediment quality are suggested to be the main cause of the variation. These results will be used as baseline information to properly manage hard clam shell resources in Panguil Bay
Does frequency of protein supplementation affect performance of cattle under grazing in tropical pastures?
Our objective was to evaluate the effects of protein supplementation frequency on performance and voluntary intake of cattle under grazing in tropical pastures by using a meta-analytical approach. The dataset used to evaluate the voluntary intake was compiled from 18 experiments carried out in Brazil between 2009 and 2021, totaling 75 treatment means. In order to evaluate the animal performance, treatment means were collected from 19 experiments carried out in Brazil between 2003 and 2018, totaling 69 treatment means. The data were analyzed using meta-analysis techniques, considering the random effect of the experiments on the model parameters. There was no effect of supplementation (P > 0.11) or supplementation frequency (P > 0.18) on forage intake and dietary digested organic matter content (DOM). On the other hand, supplementation increased (P 0.84). The ADG increased linearly (P 0.05) among supplementation frequencies. The additional weight gain (AWG) caused by supplementation decreased as forage CP increased and became null at 150 g CP/kg dry matter. There was a quadratic pattern (P 0.05). Maximal responses occur when 5.0 g of supplement and 1.14 g of supplemental CP per kg BW were provided. Reducing protein supplementation frequency down to thrice a week does not affect voluntary intake and performance of cattle under grazing in tropical pastures. There is a positive response to protein supplementation on animal performance even with medium to high-quality forages. However, that response decreases as forage CP increases and becomes null at 150 CP/kg dry matter
Presolar Grains from Novae: Evidence from Neon and Helium Isotopes in Comet Dust Collections
Presolar grains in meteorites and interplanetary dust particles (IDPs) carry
non-solar isotopic signatures pointing to origins in supernovae, giant stars,
and possibly other stellar sources. There have been suggestions that some of
these grains condensed in the ejecta of classical nova outbursts, but the
evidence is ambiguous. We report neon and helium compositions in particles
captured on stratospheric collectors flown to sample materials from comets
26P/Grigg-Skjellerup and 55P/Tempel-Tuttle that point to condensation of their
gas carriers in the ejecta of a neon (ONe) nova. The absence of detectable 3He
in these particles indicates space exposure to solar wind (SW) irradiation of a
few decades at most, consistent with origins in cometary dust streams. Measured
4He/20Ne, 20Ne/22Ne, 21Ne/22Ne and 20Ne/21Ne isotope ratios, and a low upper
limit on 3He/4He, are in accord with calculations of nucleosynthesis in neon
nova outbursts. Of these, the uniquely low 4He/20Ne and high 20Ne/22Ne ratios
are the most diagnostic, reflecting the large predicted 20Ne abundances in the
ejecta of such novae. The correspondence of measured Ne and He compositions in
cometary matter with theoretical predictions is evidence for the presence of
presolar grains from novae in the early solar system.Comment: As appeared in the Astrophysical Journa
Análise comparativa da postura ortostática entre mulheres fisicamente activas e sedentárias
Foi objectivo deste trabalho comparar a postura ortostática entre mulheres fisicamente
activas e sedentárias. Foram estudados 60 sujeitos do sexo feminino, saudáveis e não grávidas.
Trinta mulheres incluĂram o grupo das fisicamente activas (GFA) e outras trinta no grupo das
sedentárias (GS). Os sujeitos foram fotografados nos planos sagital direito e esquerdo, frontal
anterior e posterior na posição ortostática, com uma câmara digital com uma resolução fotográfica
de 10.1 Megapixéis (Exilim, EX-Z29, Casio, Tóquio, Japão). A avaliação postural foi efectuada com
recurso a uma tĂ©cnica fotogramĂ©trica e utilizando um software especĂfico (SAPo, v. 0.86,
Universidade de São Paulo, Brasil). Os ângulos Q dos membros inferiores direito e esquerdo foram
superiores no GFA do que no GS. A assimetria das omoplatas relativamente Ă T3 apresentou
valores médios superiores no GFA do que no GS. Os alinhamento horizontal da cabeça foi
superiores no GFA do que no GS. O alinhamento vertical do corpo foi inferior no GFA do que no
GS. Em sĂntese, o GFA tende apresentar uma postura ortostática que procura promover uma
quantidade inferior de esforço e/ou de sobrecarga mecânica sobre o aparelho locomotor do que o
GS
Integrating cogeneration and intermittent waste-heat recovery in food processing: Microturbines vs. ORC systems in the coffee roasting industry
Coffee roasting is a highly energy intensive process wherein a large quantity of heat is discharged from the stack at medium-to-high temperatures. Much of the heat is released from the afterburner, which is required to remove volatile organic compounds and other pollutants from the flue gases. In this work, intermittent waste-heat recovery via thermal energy storage (TES) and organic Rankine cycles (ORCs) is compared to combined heat and power (CHP) based on micro gas-turbines (MGTs) for a coffee roasting plant. With regard to the former, a promising solution is proposed that involves recovering waste heat from the flue gas stream by partial hot-gas recycling at the rotating drum coffee roaster, and coupling this to a thermal store and an ORC engine for power generation. The two solutions (CHP + MGT prime mover vs. waste-heat recovery + ORC engine) are investigated based on mass and energy balances, and a cost assessment methodology is adopted to compare the profitability of three system configurations integrated into the selected roasting process. The case study involves a major Italian roasting plant with a 3,000 kg per hour coffee production capacity. Three options are investigated: (i) intermittent waste-heat recovery from the hot flue-gases with an ORC engine coupled to a TES system; (ii) regenerative topping MGT coupled to the existing modulating gas burner to generate hot air for the roasting process; and (iii) non-regenerative topping MGT with direct recovery of the turbine outlet air for the roasting process. The results show that the profitability of these investments is highly influenced by the natural gas and electricity prices and by the coffee roasting production capacity. The CHP solution via an MGT appears as a more profitable option than waste-heat recovery via an ORC engine primarily due to the intermittency of the heat-source availability and the high electricity cost relative to the cost of natural gas
Low Energy Branes, Effective Theory and Cosmology
The low energy regime of cosmological BPS-brane configurations with a bulk
scalar field is studied. We construct a systematic method to obtain
five-dimensional solutions to the full system of equations governing the
geometry and dynamics of the bulk. This is done for an arbitrary bulk scalar
field potential and taking into account the presence of matter on the branes.
The method, valid in the low energy regime, is a linear expansion of the system
about the static vacuum solution. Additionally, we develop a four-dimensional
effective theory describing the evolution of the system. At the lowest order in
the expansion, the effective theory is a bi-scalar tensor theory of gravity.
One of the main features of this theory is that the scalar fields can be
stabilized naturally without the introduction of additional mechanisms,
allowing satisfactory agreement between the model and current observational
constraints. The special case of the Randall-Sundrum model is discussed.Comment: 19 pages, 4 figure
The role of suspended particulate matter in the distribution and structure of macrobenthic communities in the Belgian part of the North Sea
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